<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>写出⼀个1到10 的数组，少写⼀个数字，利⽤函数将少写的数字找出来</title>
</head>
<body>
  <script>
    function fn() {
      var arr = [1, 2, 3, 4, 6, 7, 8, 9, 10]
      var res = 0
      var num = 55
      for(let i = 0; i < arr.length; i++) {
        res += arr[i]
      }
      return '少写一个数字：' + (num - res)
    }
    console.log(fn())
  </script>
</body>
</html>